Method of separating the constituents of gaseous mixtures



Oct. 31, 1950 A. J. FAUSEK ETAL 2,527,623

METHOD OF SEPARATING THE CONSTITUENTS ATTORNEY I Patented Oct. 31, 1950 METHOD OF SEPARATING THE CONSTITU- ENTS OF GASEOUS MIXTURES Arthur J. Fausek and Irwin: F. Fausek, Clayton, Mo.

Application October 23, 1944, Serial No. 559,890

4 Claims. (01. (WP-175.5)

This invention relates generally to the separation of the constituents of gases by the liquei'actior: and rectification process, and more specifically to an improved method oi recovering oxygen and nitrogen from atmosphere and the removal from the atmosphere being treated, and from the separated liquid oxygen, of acetylene and other hydrocarbons present therein, the predominant object of the invention being to provide an improved method in the use of which liquid oxygen may be recovered from atmosphere which is free from acetylene and other hydrocarbons that may have been originally present in the high pressure air under treatment, and in the separated liquid oxygen prior to its final delivery from the liquefaction and rectification column.

It is generally believed by persons familiar with the subject that many explosions in oxygen columns are attributable to the presence in the columns of acetylene. Acetylene may be present in the crude, high pressure air delivered to the columns, or it may be produced as aresult of the breakdown of the lubricating oils employed in the air compressors which deliver air to the columns. Oxygen boils at -183 C. and acetylene freezes at 81 0., hence substantially all of the acetylene entering an oxygen column will remain, unless some provision is made for the elimination of the acetylene.

The predominant object of the present invention, therefore, is to provide an improved method of separating the constituents of atmosphere so that during the course of such separation acetylene, and other hydrocarbons, are completely eliminated with the result that liquid oxygen finally delivered irom the column is entirely tree from acetylene, or other hydrocarbons.

In the drawing, wherein is illustrated a single diagrammatical view which illustrates the improved method 0! the present invention, C designates, generally, a liquefaction and rectification column. The column C comprises a vertically disposed housing, in the upper portion of which is arranged a plurality of conventional rectification trays l disposed in the usual vertical spaced relation. Arranged within the housing of the column 0, beneath the upper rectification trays I is a dephlegmator 2, said dephlegmator comprising a bottom wall 3, an upper, hollow head 4 spaced Vertically irom said bottom wall, and a bank of tubes 5 which are supported by said bottom wall and said head so that they communicate at their upper ends with the interior oi the hollow head, and at their lower ends with the portion of the housing of the column located beneath the bottom wall of the dephlegmator. At the bottom of the dephlegmator 2 an annular portion 8 is present which is hollow so as to provide an annular chamber I, the tubes of an outer, annular row of tubes 8 of the dephlegmator 2 communicating at their upper ends with the interior of the hollow dephlegmator head 4, and at their lower ends with said annular chamber I.

Located within the housing of the column C beneath the dephlegmator 2 is a group of rectification trays 9 and a group oi rectification trays Ill, said groups of rectification trays 9 and I0 having interposed therebetween an expansion valve i I. The extreme lower portion of the housing of the column C provides the boiling pot of the column wherein a plurality of coils l2 are located, and located within the housing of the column C, between the lowermost tray of the group of rectification trays I0 and the boiling pot coils I2, is a discharge head Hi. The boiling pot coils l2 are connected by a conductor is to the expansion valve II, and also, a conductor i5 leads from the bottom of the boiling pot of the column C to the discharge point It oi! said conductor which is located intermediate 01 the height of the group of rectification trays l. The conductor I5 is provided with a valve It for controlling passage of medium therethrough.

The apparatus for carrying out the present in-- vention which is illustrated in the drawing, includes a conductor H which conducts high-pressure air from a suitable compressor (not shown) to a housing I8 wherein is disposed one or more electrical heating elements is. During passage of the high-pressure air through the housing l8, which functions as a furnace, acetylene, and other hydrocarbons carried by the incoming air are burned so that the high-pressure air which leaves the housing I8 is substantially free of such hydrocarbons. From the housing I8 the high-pressure air passes by way of a conductor 20 to a cooler 2|, and thence by way of the conductors 22 to and through a plurality of caustic dryers 23 wherein entrained moisture and products of combustion are removed. After passing through the last dryer 23 the high-pressure air passes through a conductor 24 to a heat interchanger 25.

High-pressure air which passes from the dryers 23 to the heat interchanger 25 passes from said portion of said divided air passing from the receiver 11 by way of the conductor 85 to and through a iiquener 8|, and thence by way of the conductor 82 to the coils l2 within the boiling pot or the column C. From the boiling pot coils the medium delivered thereto by the conductor 82 passes to the expansion valve I I for descent through the trays II.

Connected into the annular chamber 1 at the bottom of the dephlegmator 2 is a crude nitrogen conductor 83 which leads from said annular chamber 1 to a sub-cooler 34, the nitrogen which passes to said sub-cooler by way of the conductor 88 passing from said sub-cooler by way of a conductor 85 to the top of the column C where it is discharged at the point 85'. The conductor 85 is provided with a valve 88 which is operable to control passage of nitrogen through said conductor, and said conductor 85 extends through a condensing unit 81 so that nitrogen conducted by said conductor 35 to the top of the column is passed through said condensing unit.

Under certain circumstances, however, it may be desirable to cause the nitrogen which passes by way of the conductor 85 to the top of the column, to by-pass the condensing unit 81 and not pass therethrough. For this purpose a by-pass conductor 88 is provided which connects at its opposite ends into the conductor 35 below and above the condensing unit 81, and which is provided with a valve 38. When it is desired to cause the nitrogen moving through the conductor 85 to the top of the column to pass through the condensing unit 81 the valve 88 of the conductor 35 is opened and the valve 38 of the by-pass conductor 88 is closed. On the other hand, when it is desired that the nitrogen moving to the top of the column through the conductor 85 shall bypass the condensing unit 81, the valve 88 of the conductor 35 is. closed while the valve 88 of the by-pass conductor 88 is opened.

Oxygen may be taken oil of the column in either liquid form or gaseous tom, the liquid oxygen being taken on of the column at a low point of the dephlegmator 2 through the conductor 48 which is connected into a conductor 4|. Also the conductor 4| has connected therein a gaseous oxygen conductor 42 which communicates also with the interior of the column C at a point immediately above the dephlegmator 2. The upper end of the conductor 4| is connected to the upper portion of the condensing unit 31 by a conductor 43, there being provided a valve 44 which controls passage of gaseous oxygen through said conductor 48 to the upper portion of the condensing unit 31. Also,-a conductor 45 is connected into the conductor 4|, arTd th is conductor leads to a portion 01' the sub-cooler 84, medium delivered to the sub-cooler 34 by the conductor 45 being conducted therefrom by a conductor 48 to a portion of the llqueiier 8|, and from liquefler by a conductor 41 to the heat interchanger, from which it is delivered by a conductor 48. The conductor 4| is provided with valves 48- and ill at opposite sides of the point where the conductor 45 connects into said conductor 4|, and also, said conductor 4| is provided with a valve which is located below the point where the conductor 48 connects into said conductor 4|. Additionally, the condensingunit 81 has connected into its lower portion a conductor 52 which is provided-with a valve 58.

Communicating with the top or the column C is nitrogen conductor 54 which includes a portion 54a that passes through the condensing unit 81.

and a portion 5423 which provides a nitrogen bypass around said condensing unit 81. The nitrogen conductor portions are interconnected above the condensing unit and below same, there being provided valves 55 and 58 which are operable in 5 an obvious manner to direct nitrogen coming irom the top of the column either through the condensing unit 31 or around same. The conductor 54 extends to a portion of the sub-cooler 84, and from said sub-cooler nitrogen is conducted by a conductor 51 to the liquefler 3|, and from said liquefier by a conductor 58 to the heat interchanger 25, nitrogen passing from the heat interchanger by way 0! a conductor 58.

In separating the constituents 0! atmosphere in accordance with the presentinvention, and with the aid of such an apparatus as that illustrated in the drawing, high-pressure air moving to the column 0 passes through the housing |8 wherein acetylene and other hydrocarbons carried by the high-pressure air are consumed -by the heat of the electric heating elements I! within said housing I8. The high pressure air then 'passes through the cooler 2| and the caustic dryers 23, and through the heat interchanger to the receiver 21 wherein said high-pressure air is divided into two parts, one part passing through the liquefier 3| to the boiling pot coils l2 for subsequent delivery to the expansion valve and the other part being delivered by the expansion engine 28 to the discharge head II in the upper portion of the boiling pot of the column C. Also, crude liquid oxygen is conducted by the conductor l5 from the boiling pot of the column C to the discharge point l5 oi said conductor |5 for descent through the upper portion of the column.

The column C functions in the usual and well understood manner to separate from the atmosphere being acted on, by liquefaction and rectification, oxygen and nitrogen forming parts thereof,

a body of liquid oxygen 0a gathering at the dephlegmator 2, and a body of crude liquid oxygen Obgathering in the boiling pot of the column.

Also, a body of crude nitrogen gathers in the chamber 1 provided by the annular portion 8 at the bottom of the dephlegmator 2. As previously stated, crude nitrogen passes from the annular chamber 1 by way of the conductor 88, through the sub-cooler 84, and from said sub-cooler by way of the conductor 35, to the top of the column, while crude, liquid oxygen passes through the conductor I5 from the boiling pot of the column to a point intermediate 01' the height 0! the trays the nitrogen being either passed through the condensing unit 81 or around same, as desired, by

manipulation oi the valves 85 and 88.

Liquid oxygen may be withdrawn directly from the body of oxygen 0d, at the dephlegmator 2,

through a portion of the conductor 4|, by closing the valve 50 and opening the valve 5|, and also 60 gaseous oxygen may be drawn from the portion of the column C at the upper end of the dephlegmator by closing the valve 48 .and opening the valve 44, said gaseous oxygen being discharged into the condensing-unit 81 where it is converted .65 into a liquid state. Additionally, liquid oxygen from the body of oxygen 00. may be withdrawn from the lower portion of the dephlegmator 2,

and gaseous oxygen may be withdrawn from the portion of the column immediately above the dephlegmator 2, and such liquid and gaseous oxygen may be mixed and directed through the conductor 45, and thence successively through the sub-cooler I4, liqueiier 3|, and heat interchanger 25 to the outlet conductor 48 thereof. When liquid and gaseous oxygen is to be mixed as described.

obtained-from gaseous oxygen within the con-.

densing unit 31 is purer than the liquid oxygen received from the lower portion of the dephlegmator 2, in that the liquid oxygen from the lower portion of the dephlegmator may contain some acetylene, or other hydrocarbons, which have riot been consumed in the housing l8. However, substantially all of the acetylene, or other hydrocarbons, are burned as the incoming high-pressure air passes through the housing I 8, and therefore very little of the undesirable hydrocarbons will be present in the liquid oxygen withdrawn from the lower portion of the dephlegmator 2.

The nitrogen that passes from the top of the column 0 through the conductor 54, passes through or around the condensing unit 31, the valves 55 and 56 being actuated to cause the nitrogen to follow the desired course, and said nitrogen is successively passed through the sub-cooler 34, the liquefier 31 and the heat interchanger 25, to provide the refrigeration necessary for the performance by said parts of the apparatus of their intended functions.

It is obvious, therefore, that the improved method of the present invention provides for the removal of acetylene, or other hydrocarbons in two ways, so as to produce oxygen which is free from such hydrocarbons, first, by burning the acetylene, or other hydrocarbons, as they pass with the incoming high-pressure air through the housing l8, and, secondly, by recondensing gaseous oxygen, which, because of its gaseous state, is free from such hydrocarbons, in the condensing unit 31.

We claim:

1. The method of separating the constituents of atmosphere under pressure so as to obtain therefrom oxygen of a purity suitable for commercial purposes, said method comprising preliminarily removing from the atmosphere being treated hydrocarbons contained therein by burning away said hydrocarbons, cooling the atmosphere from which hydrocarbons'have been re-' therefrom oxygen of a purity suitable for commercial purposes, said method comprising preliminarily removing from the atmosphere being treated hydrocarbons contained therein by burning awaysaid hydrocarbons, cooling the atmosphere from which hydrocarbons. have been removed, directing the cooled atmosphere to a liquefaction and rectification therein which separates of the atmosphere being reated within the liquefaction. and rectificatidn column, withdrawing from the liquefaction and rectification column oxygen in gaseous form, and thereafter liquefying said gaseous oxygen, with the aid of colder nitrogen recovered from the atmosphere being treated within theliquefaction and rectification column. 1

3. The method of separating the constituents of atmosphere under pressure so as to obtain therefrom oxygen of a purity suitable for commercial purposes, said method comprising preliminarily removing from the atmosphere being treated hydrocarbons contained therein by burning away said hydrocarbons, cooling the atmosphere from which hydrocarbons have been removed, directing the cooled atmosphere to a liquefaction and rectification column for treatment therein which separates the oxygen and nitrogen of the atmosphere being treated within the liquefaction and rectification column, and withdrawing oxygen and nitrogen from the liquefaction and rectification column.

4. The method of separating the constituents of atmosphere under pressure soas to obtain therefrom oxygen of a purity suitable for commercial purposes, said method comprising preliminarily removing from the atmosphere bein treated hydrocarbonsv contained therein by burning away said hydrocarbons, cooling the atmosphere from which hydrocarbons have been removed, and directing the cooled atmosphere to a liquefaction and rectification column for treatment therein which separates the oxygen and nitrogen of the atmosphere being treated within the liquefaction and rectification column.

ARTHUR J. FAUSEK. IRWING F. FAUSEK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,549,236 Van Nuys Aug. 11, 1925 1,774,462 Van Nuys et al. Aug. 26, 1930 1,785,491 Messer Dec. 16, 1930 1,958,553 Van Nuys May 15, 1934 2,040,107 Schlitt May 12, 1938 2,154,668 De Bauire Apr. 18, 1939 2,238,012 4 Clark Apr. 8, 1941 2,287,137 Ross June 23, 1942 2,287,158 Yendall June 23, 1942 2,327,459 Rice Aug. 24, 1943 2,406,003 Dennis Aug. 20, 1946 2,409,458 Van Nuys Oct. 15, 1946 2,411,711 De Baufre Nov. 26, 1946 2,423,273 Van Nuys July 1. 1947 column for treatment \the oxygen and nitrogen, 

